Welcome to Just answer !
Well, i think she may perhaps be suffering from Depression and it is under the clout of depression that she is being so negative about you and everything else in the marriage. Also, since once she mentioned that she fears about her safety , this incident spells of paranoid behaviour , which also can be an extention of a depressive condition or it can be a different psychiatry condition altogether ...
So, yes her mood changes as narrated by you seem to me rather abrupt and possibly driven by an underlying psychopathology aka psychological condition like Depression or psychosis ...so in this regard consulting a psychiatrist to evaluate her properly should be the first step , because it is quite likely that her decision to end marraige is not hers but it is taken under the influence of underlying psychological condition that she is in at the moment and on top of it she is unaware / lack insight into all of this happening around her ..
So, yes a psychiatrist would be te first step here for proper evaluation of her and if there is a clearance from the psychiatrist 's side then you may proceed to a counselor ...
I hope this helps..
Wish you all the best..
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